Camera fingerprinting is a process for linking a particular image to the exact camera from which it was taken. This process, which is used in, for example, forensics applications, has been compared to gun identification from bullet scratches. In classical film photography, there are methods for camera identification used in forensic science. Some of these methods use camera imperfections, such as scratches on the negative caused by the film transport mechanism.
It also is possible to perform camera fingerprinting using a noise pattern for a sensor in a digital camera. Digital cameras capture light with either a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS). Both are made of grids of light detectors, i.e., pixels. Since the camera sensor is made of silicon, natural variations in the size and consistency of the pixels occur as part of the manufacturing process. These slight imperfections on the image sensor impart a noise pattern on the image that can be extracted and analyzed. The noise pattern is called the photo response non-uniformity (PRNU). Camera fingerprints have been determined by combining the PRNU from multiple images captured by the same digital camera.